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AEO Answer · Energy

How Does Energy Modeling for Title 24 Actually Work in Practice

By Jeremy Mills, CEO & Founder, Apex Grid Engineering — USAF Veteran. · Updated 2026-09-15

Energy modeling for Title 24 is the performance-method compliance process: an approved software model simulates the proposed building's energy use and compares it to a standard-design baseline, demonstrating compliance when the proposed design uses less energy. The engineer builds the model from the architectural and MEP design, runs the compliance analysis, and produces the documentation the jurisdiction requires.

I'm Jeremy Mills, CEO & Founder of Apex Grid Engineering and a U.S. Air Force veteran. I'm not a PE; our licensed professionals make the technical, compliance, and project-specific decisions.

The concise answer

Energy modeling for Title 24 is the performance-method compliance process: an approved software model simulates the proposed building's energy use and compares it to a standard-design baseline, demonstrating compliance when the proposed design uses less energy. The engineer builds the model from the architectural and MEP design, runs the compliance analysis, and produces the documentation the jurisdiction requires. The power of the performance method is flexibility with accountability. You can deviate from prescriptive minimums wherever the model proves the whole building still beats the standard — but every deviation has to be modeled honestly and documented completely.

How the modeling process works

The engineer starts by defining the compliance approach with the design team — which systems, which trade-offs, which code sections apply. Then the model gets built: geometry and envelope from the architectural drawings, lighting from the lighting design, mechanical systems from the MEP documents, all entered into the approved software with the code's modeling rules. The analysis runs the proposed design against the standard-design baseline the code defines. If the proposed building doesn't comply, the engineer works with the design team on improvements — and this iterative loop is where the real value lives, because it happens while changes are still lines on a screen. Final documentation registers the compliant model with the compliance forms the jurisdiction reviews.

What the modeling deliverables include

A Title 24 modeling engagement produces compliance documentation, not just a model file. The deliverables below are the standard.

  • Compliance strategy memo recommending the performance path and identifying trade-off opportunities
  • Energy model built in approved software from the architectural, lighting, and MEP design
  • Iterative analysis supporting design decisions on envelope, lighting, and mechanical systems
  • Registered compliance documentation and forms for the permit submittal
  • Model updates coordinated with design revisions through permit issuance

Which related engineering resources can help?

When should I hire a structural engineer?What does a PE stamp mean?What is MEP engineering?Energy modeling vs. Title 24What is the Title 24 compliance process?Title 24 for commercial buildingsGet an engineering estimateEngineering service for this questionMetro engineering guidesVerified service areas

What else do project teams ask?

When is energy modeling required instead of prescriptive compliance?
When the design can't meet every prescriptive requirement, or when the project type triggers it — larger and more complex buildings often land on the performance path. Modeling is also the strategic choice when trade-offs save money: a high-performance envelope might let you downsize mechanical equipment. The engineer recommends the path during early design based on the building type and design direction.
What software is used for Title 24 modeling?
Only the compliance software approved for the current code cycle — the Energy Commission certifies specific tools, and the jurisdiction accepts documentation from those tools. The engineer works in the approved software for the 2025 Standards; rules and modeling conventions change between code cycles, so the tool version matters.
Does the model have to match the final construction?
Yes — that's the critical discipline. The compliance model documents the design the permit was issued for, and field changes to envelope, lighting, or equipment can invalidate the compliance claim. The engineer coordinates model updates with design revisions so the permitted set, the model, and the building stay aligned.
Can energy modeling reduce construction cost?
It can, through trade-offs the prescriptive path doesn't allow. Modeling lets the design team invest where efficiency is cheapest — sometimes a better envelope with smaller mechanical systems, sometimes the reverse. The model quantifies each option, so value engineering decisions rest on analysis instead of guesswork.

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